Heavy vehicles for use off or on the road and particularly the largest size semi-trailers and tractors employ wheel studs or lugs which all too often become stuck, broken or damaged and are difficult to remove. One common problem occurs with the Budd-style lug bolt or stud which is hollow and is held in place with a retaining bolt mounted from the brake drum portion of the wheel. Tools heretofore available for removing studs of this kind were likely to become broken or were ineffective in operation. One prior stud extractor is constructed to make point contact with the stud, for example by using fixed teeth or jaws. In one tool of this type two hardened steel jaws were mounted on the inside of the stud receiving opening. Jaws of this kind tend to slip because point contact allows abrasion of metal forming the surface of the stud. Another type of extractor has a plurality of rolls, e.g. three rolls, each mounted in a ramp or cam track spaced evenly around the stud. Here again, the tool makes point contact with the stud. The point contact allows metal to be scraped from the surface of the stud, enabling it to slip when torque is applied to the tool. This is especially true when the surface of the stud is covered with screw threads.
A further disadvantage of prior tools is the complex shape of the opening used to receive the stud. Forming such an opening can require several successive machining operations. This makes the tool expensive to produce. A further shortcoming is that gripping rollers previously proposed can become cocked, misaligned and/or stuck in position and therefore will not operate properly.
In view of these deficiencies of the prior art it is an objective of the invention to provide a tool of the type described which has a single smoothly contoured recess that lends itself to high-speed automated production and which holds both the stud and a gripping roll for engaging the stud.
Another object is to provide a tool with a contoured wall that engages the stud over a large portion of its surface so that the stud can be held over an extended area approximating one-half of its surface, thereby allowing it to be pressed more firmly against the gripping roll to reduce slippage.
Yet another object of the invention is to provide a gripping roll with extended flat alignment surfaces on each end to reliably hold the gripping roll in place so that it will move freely within its opening, ready to engage the broken or stuck stud when pressure is applied to the tool.